Signaling pathways in early onset sporadic breast cancer of patients in Indonesia.

Aim: to determine signaling pathways in breast cancers from patients aged 35 years old or younger and patients aged more than 35 years old.

Methods: this was a cross-sectional, comparative study of female breast cancer patients who were recruited and divided into two age groups, i.e. 35 years or younger and more than 35 years old. Specimens were obtained by biopsy or surgical removal of the tumors and were confirmed by histopathological examination. The expression of ER, IGF-1R, Her-2, MAPK, and cyclin D1 were measured using immunohistochemistry.

Results: ninety-three patients were recruited from September 2004 to December 2005. Forty-three patients were 35 years or younger. More than 90% of the patients within the two groups showed invasive ductal carcinomas and more than half of these tumors were grade 2. Immunohistochemical staining was successfully done in 90 patients. ER-alpha expression was negative in 33 breast cancers (78.6%) from patients less than 35 years old and 32 cancers (66.7%) of older patients. The expressions of IGF-1R, Her-2, MAPK, and cyclin D1 were positive, respectively in 17 (40.5%), 11 (26.2%), 28 (66.7%), and 7 (16.7%) cancers within the group of patients 35 years old or younger, and, respectively in 18 (37.5%), 11 (22.9%), 37 (77.1%), and 9 (18.8%) of cancers from patients more than 35 years old.

Conclusion: there were no statistically significant differences in the expression of any of the biomarkers between the two groups. In all patients, ER was negative in 72.2% cases and MAPK was positive in 76.7% cases. Patients aged 35 years or younger showed similar ER, IGF-1R, Her-2, MAPK, and cyclin D1 expressions compared to cancers from patients more than 35 years old. These were predominantly ER-negative, suggesting that estrogen does not play a dominant role in their growth. The frequent expression of MAPK in these cancers raises the possibility that growth factors play a dominant role in their growth.